Ruby
Corundum var. Ruby · Precious Gemstone
Crystal System
Trigonal, typically forming barrel-shaped, prismatic, or tabular hexagonal crystals
Mineral Group
Oxides
Chemical Formula
Al2O3 (with trace amounts of Cr3+ substituting for Al)
Formation Process
Metamorphic and Igneous; typically forms in aluminum-rich, silica-deficient metamorphic environments such as marbles under high temperature and pressure
About This Crystal
Vivid pinkish-red to deep red rough crystal fragment, showing translucent to sub-translucent transparency with a vitreous to sub-adamantine luster and minor dark inclusions or surface matrix material
Physical Characteristics
Color is vivid red; streak is white; no true cleavage, exhibits parting along specific planes; conchoidal to uneven fracture; specific gravity is approximately 4.0; brittle tenacity; strong red fluorescence under ultraviolet light due to chromium content
Optical Properties
Uniaxial negative with strong birefringence; strong dichroism showing purplish-red and orange-red from different angles; high refractive index ranging from 1.762 to 1.770
Hardness & Durability
Origin Region
Notable sources include Myanmar (Burma), Mozambique, Madagascar, Thailand, and Sri Lanka; forms in marble-hosted deposits and alluvial gravels
Hardness & Durability
Mohs hardness of 9, making it extremely durable and second only to diamond; excellent wearability for all types of jewelry with no special cleavage concerns
Care & Maintenance
Safe for ultrasonic and steam cleaners unless heavily fractured or clarity-enhanced with glass/resin; store separately from softer gems to prevent scratching; resistant to most household chemicals
Rarity & Value
Rare to Very Rare depending on size, clarity, and depth of color; unheated stones with intense 'Pigeon's Blood' red color from traditional origins like Burma command exceptional prices; heat treatment and fracture filling are common enhancements
Special Characteristics
Exhibits strong red fluorescence under both longwave and shortwave UV light; can display asterism (star ruby) when microscopic rutile needle inclusions are present
Lore & History
Historically regarded as the 'King of Gems', associated with vitality, passion, and protection in ancient cultures; traditionally linked to the root chakra in crystal healing practices as a symbol of life force and courage